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Evaluation of changes in human corneae after femtosecond laser-assisted LASIK and ReLEx-smile using Corvis

Session Details

Session Title: Cornea

Session Date/Time: Sunday 16/02/2014 | 08:30-11:00

Paper Time: 08:42

Venue: Linhart Hall (Level -2)

First Author: : DanielKook GERMANY

Co Author(s): :    Rainer Wiltfang   Martin Bechmann   Wolfgang Mayer   Anselm Kampik   Shervin Mohi  

Abstract Details

Purpose:

To evaluate biomechanical stability and deformability of human corneae before and after two different femtosecondlaser assisted corneal refractive procedures: femtosecondlaser assisted LASIK and ReLEx-smile.

Setting:

Comparative and consecutive case study in one surgical center.

Methods:

Hundred twenty-eight eyes of 73 patients with moderate to high myopia and/or astigmatism (spherical equivalent < -10.0 dpt, astigmatism < 5.0 dpt) were measured with non-contact tonometry and ultra-high-speed camera (Corvis® ST, Oculus) before and after surgical treatment. Fourty-eight eyes were treated with the femtosecondlaser for flap generation (VisuMax®, Carl Zeiss Meditec) and ablated with an eximer laser (Mel 80 ™, Carl Zeiss Meditec). Eighty eyes were treated with an all-femto-procedure by generating an intrastromal lenticule and then extracting the lenticule through a small incision (ReLEx-smile: small incision lenticle extraction). All patients were operated by the same surgeon (RW). Preoperatively and one month to three months postoperatively following data were analyzed: UDVA, CDVA, refraction, biomicroscopy of anterior eye segment, IOP with non-contact tonometry and Goldmann tonometry and deformability of the cornea using the Corvis® ST. Data were analyzed using SPSS version 13.0 for Windows and p < 0.05 was considered as significant (t-test).

Results:

Span of patient`s age in the Femto-LASIK group was 27-46 years, in the ReLEx-smile group 22-59 years. Preoperative spherical equivalent was -3.2 dpt in the Femto-LASIK group and -4.8 dpt in the ReLEx smile group. Almost all parameters generated by Corvis® ST showed significant changes comparing pre- to postoperative data. Significant changes ware noted between both treatment groups postoperatively (IOP Corvis tonometry, Pachy, A1 Deflection Amp., A1 Deflection Length, Radius, Radius (3P), A1 Deformation Amp., A1 Time). Matched pair subgroup analysis of eyes with equal amount of reduced tissue (n=53; 24 eyes Femto-LASIK; 29 eyes ReLEx smile; p=0.05) showed no significant changes in parameters measured with Corvis® ST.

Conclusions:

Corneal biomechanical parameters showed statistical significant differences after refractive surgery measured with Corvis® ST either after Femto-LASIK and after ReLEx-smile. When equal amount of tissue was extracted, Femto-LASIK showed no significant changes compared to ReLEx smile. FINANCIAL INTEREST: NONE